ceph clients don't honour ceph-public-network

This actually afftects all ceph client charms since they all use private-address:

http://bazaar.launchpad.net/~charm-helpers/charm-helpers/devel/view/head:/charmhelpers/contrib/storage/linux/ceph.py#L205

Having taken a closer look at some of the code it seems that this function is not actually used by every charm. Need to double check all clients to confirm and if true we should delete this code.

The cinder glance and nova-compute charms all use:

class CephContext(OSContextGenerator):
    """Generates context for /etc/ceph/ceph.conf templates."""
    interfaces = ['ceph']

    def __call__(self):
        if not relation_ids('ceph'):
            return {}

        log('Generating template context for ceph', level=DEBUG)
        mon_hosts = []
        auth = None
        key = None
        use_syslog = str(config('use-syslog')).lower()
        for rid in relation_ids('ceph'):
            for unit in related_units(rid):
                auth = relation_get('auth', rid=rid, unit=unit)
                key = relation_get('key', rid=rid, unit=unit)
                ceph_pub_addr = relation_get('ceph-public-address', rid=rid,
                                             unit=unit)
                unit_priv_addr = relation_get('private-address', rid=rid,
                                              unit=unit)
                ceph_addr = ceph_pub_addr or unit_priv_addr
                ceph_addr = format_ipv6_addr(ceph_addr) or ceph_addr
                mon_hosts.append(ceph_addr)